Is Benadryl Safe With Children's Cough DM (Dextromethorphan)?

In our latest question and answer, the pharmacist discusses whether or not Benadryl (diphenhydramine) and dextromethorphan can be used together.


Can Children Benadryl be taken with Children's Cough DM?

Asked by Tiffany On Dec 31, 2021

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Jan 01, 2022
Last updated Mar 03, 2022

Key points

  • There is no known drug interaction between Benadryl (diphenhydramine) and Children's Cough DM (dextromethorphan).
  • Some over-the-counter products even contain both ingredients, such as 'Diabetic Tussin'.
  • Although there is no drug interaction between Benadryl and Children's Cough DM, both can cause drowsiness, so you may feel tired after taking them.

Hello and thanks for reaching out to us! I'm more than happy to answer this for you.

In your question, you don't mention exactly what product you are referring to with 'Children's Cough DM'.

However, this product name is shared between many different store-brand (i.e. generic) cough medicines, like these products available from Walgreens, CVS, and Walmart:

Childrens cough DM boxes

All of these 'Children's Cough DM' products are made and marketed to be compared to the brand name product, Children's Delsym.

Childrens Delsym

All of these products contain the same active ingredient, dextromethorphan.

So, we are looking at whether or not dextromethorphan and Benadryl (which contains the active ingredient diphenhydramine) can be taken together.

Can You Use Both Together?

As mentioned in the section above, Children's Cough DM products and brand name Delsym contain the cough suppressant, dextromethorphan.

It is safe to take Benadryl (diphenhydramine), a sedating antihistamine, and dextromethorphan together. There are no know interactions between the two drugs.

In fact, it's not uncommon for some over-the-counter cough/cold products to contain both an antihistamine, like Benadryl, and dextromethorphan.

For example, Diabetic Tussin has both drugs in it.

Diabetic Tussin Box

Side Effects?

I will say that even though Benadryl and dextromethorphan can be used together (and may even be combined into a single product), both can make you a little tired.

Benadryl is well-known to cause sedation, which is why it is so commonly used as a sleep aid.

While dextromethorphan generally doesn't cause as much sedation as Benadryl, it still does cause drowsiness in some individuals. Therefore, if you combine both, just be aware you're likely to feel tired since both can have this effect.

Final Words

Thanks again for reaching out to us. Feel free to contact us with any further questions!


  • Diphenhydramine Monograph, PubChem
  • Dextromethorphan Monograph, PubChem
  • DailyMed Diphenhydramine Monograph, DailyMed
  • DailyMed Dextromethorphan Monograph, DailyMed

About the Pharmacist

Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 11 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication related questions!

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